Rotator Cuff Injuries

The rotator cuff is a group of four muscles and their interconnected tendons that help provide stability and movement to the shoulder. It is the 3rd most common musculoskeletal site of pain after the lower back and knee, but reportedly has the highest impact on mental and physical quality of life (1). The presence of rotator cuff pain can be very variable with up to 50% of patients still reporting persistent pain 6–12 months after seeking an initial primary care consultation (doctor or other health professional) (2). The term rotator cuff related shoulder pain (RCRSP), is a broad term that includes rotator cuff tendinopathy, tendinitis, tendinosis, partial thickness rotator cuff tears, atraumatic full thickness rotator cuff tears, impingement and subacromial pain. Together these account for 50%–85% of shoulder pain. These will be explored to help you gain a better understanding of shoulder pain.

Anatomy

The rotator cuff encircles the shoulder (glenohumeral) joint; the connection between the humerus (upper arm) and the shoulder blade (glenoid fossa of the scapula). The four muscles of the rotator cuff are the subscapularis, supraspinatus, infraspinatus and teres minor. Whilst many consider these muscles separate muscles with separate actions they are highly interconnected similar to the four muscles of your thigh (quadriceps). The tendons of the RC fuse into one structure, with the supraspinatus and infraspinatus fusing inseparably near their insertion. The muscular portion of teres minor and infraspinatus also fuse inseparably just proximal to the musculotendinous junction (the connection between muscle and tendon). The subscapularis and supraspinatus tendons fuse to form a sheath that surrounds the biceps tendon (2, 3, 4). Although the interwoven nature of RC, capsule and ligament tissue would improve resistance to failure under load, it negates the possibility of testing individual structural units (2). It does lead clinicians towards utilising different tests and assessments to help inform the likelihood of which structures may be more involved. The shoulder also contains bursae, the bursae are a normal part of our anatomy then are found all across the body at sites of bony prominences. In the shoulder the subacromial bursa is often continuous with subdeltoid bursa and can be normally 5.5 cm wide in size with attachments to the acromion and the supraspinatus (5). It alongside the rotator cuff (muscle and tendon) can be a source of symptoms from the rotator cuff.

(5)

It was previously a widely held belief that individuals would get shoulder pain from the close approximation of the rotator cuff and the bursa to the acromion (part of the shoulder blade), which would result in ‘pinching’ as the arm is raised typically forward, to the side or into external rotation. This was termed ‘impingement’ based on the orthopaedic tests from Dr Charles Neer and the subsequent surgery developed to fix this impingement. Hopefully this is not a diagnosis you have been given in 2023. Without diverting from addressing rotator cuff pain too much a number of great studies findings have strongly suggested we move away from this terminology. In summary;

• Pain pattern – most shoulders ‘impinge’ at 30-60 degrees the shortest subacromial distance yet classic impingement pattern of pain seen is a painful arc from 70-120 degrees (6)
• The repeated and consistent finding that the majority of tears are predominantly located within the tendon or on the articular side, instead of the bursa/acromion does not support the acromial impingement model (2).
• A number of high-quality reviews and randomised controlled trials reporting no clear benefit of Subacromial Decompression Surgery (SAD) versus exercise therapy (7) or placebo surgery (8, 9, 10).
• If SAD surgery is not superior to placebo or exercise therapy for pain and function, or doesn’t lead to reduced incidence of rotator cuff tears, does the ‘impingement’ component of the condition not really exist (8)
• As an analogy if we have a sore hamstring that hurts when we sit, the sit bones aren’t considered the problem, more that the tissue and that position are currently sensitised
• Impingement does happen as a normal act of a healthy shoulder and is not the primary cause of subacromial shoulder pain or rotator cuff pathology, nor does not need to be corrected to substantially improve pain or function (10)
• Anatomy plays a role but so do a number of other factors; one such being the biggest predictor of rehabilitation success/physiotherapy outcomes for people with shoulder pain are not mechanical features at all, but patient expectations and self-efficacy (12, 13).

Assessment and Diagnosis

To determine if the rotator cuff is the cause of someone’s shoulder pain the physiotherapist goes through a history and does a thorough assessment. To do this they will (2);

• Rule out that it pain is referred or related to another cause (e.g. from the cervical, thoracic, abdominal regions, neural or vascular tissues) – this is determined by the characteristics of the individuals pain and by combined movement tests
• Rule out that it is primarily related to a stiff shoulder (e.g. frozen shoulder, osteoarthritis, locked dislocation, neoplasm-such as osteosarcoma) – determined primarily by range of movement assessments and characteristics of symptoms.
• Rule out instability (post subluxation, dislocation or hyper-mobility syndromes) – utilising beighton hypermobility score, medical history, history of trauma and orthopaedic instability tests
• Determine factors that may contribute to poor or favourable recovery
• Determine whether a surgical opinion is needed? It is important to note here that certain rotator cuff injuries may benefit from surgical opinion; this doesn’t necessitate surgery. Signs that might suggest this include:
  • Traumatic full thickness tear <65 years old
  • Positive drop arm sign – can’t control or stop arm if let go once lifted by therapist
  • ‘Significant’ loss of muscle power
  • Tear location – rotator cuff cable
  • Tear size > 1cm (if acute) (greater than 3cm is considered large (22))

In the assessment of shoulder pain diagnosis of rotator cuff related shoulder pain (RCRSP) can be made from a detailed history of symptoms and a thorough assessment (14). Commonly reported details include;

• Pain with movement, typically abduction, flexion and/or external rotation
• Pain lying on that side – not true night pain
• Atraumatic, but can come on after an increase in shoulder based activity
• Dull ache, occasionally sharp with movement
• No neural deficits (pins and needles, numbness, power loss in multiple other muscles)
• Pain location is usual anterolateral shoulder

As part of confirming or determining diagnosis a common question is do I need imaging or how do we interpret what my scan says? Multiple studies have looked at the utility of imaging (US or MRI) for rotator cuff related pain. These studies image people with (symptomatic) and without (asymptomatic) shoulder pain, typically their painful and non-painful shoulders. Asymptomatic rotator cuff abnormality (tear, tendinosis, calcification, atrophy) was noted in 75% of shoulders (16) but can be up to 96% (17). Subacromial bursitis or bursal thickening has also been reported commonly in pain free shoulders 74% in one study (18) and 78% of the time in another (16). In a third study there was an equal percentage of bursitis in painful and pain free shoulders 70% (17). Studies have also looked at the presence of partial thickness tears, with prevalence up to 40% in pain free shoulders (18, 19). Interestingly a study by Minagawa has shown we are twice as likely to have an asymptomatic tear as to have a symptomatic tear (20, see graph below). This is potentially as non-traumatic partial thickness tears can be a normal part of aging (21, 22). The number of rotator cuff tears significantly increases with age, particularly from the age of 50 (20). The findings from numerous imaging studies suggest reliance on imaging is potentially problematic due to the large numbers of people without symptoms demonstrating abnormalities or structural failure (2, 16, 21). Clinical diagnosis is established through discussion with patients and clinical assessment procedures, which then may be supported by imaging studies (2, 14). The most reassuring aspect of this for people with shoulder pain is the finding of partial thickness tears may be a normal imaging finding before their pain began or need to heal to have symptom resolution (2). The combination of these factors lead to imaging generally not being necessary for diagnosis or management of RCRSP.

Why did I get shoulder pain?

If the imaging findings of the shoulder don’t explain why or exactly what may be sore, the logical next question is why is my shoulder sore then? The development of shoulder pain is commonly multifactorial, with numerous contributors to the development of symptoms. These can include;

• Excessive or mal-adaptive loads/stress
• Overuse or Underuse
• Psychosocial factors
• Age
• Occupation
• Biochemical, patho-anatomical, peripheral and central sensitisation, sensory-motor cortex changes
• Genetics
• Hormonal influences
• Lifestyle factors such as smoking, alcohol consumption, comorbidities and level of education (23)

To help understand why someone develops shoulder pain it is helpful to focus on the terms capacity and load (internal and external). We can consider the capacity of the shoulder, its ability to perform activities with volume and intensity without pain or injury. This could be quantified with numerous physical assessment tests. The things we expose our shoulder to during work, training, competition and leisure are the external loads placed on our shoulder (weight, repetitions, holes of golf, hours of manual work ect) whilst the concept of internal load incorporates all the psychophysiological responses occurring during the execution of these tasks (21, 24). The development of pain can be due to absolute overload due to more external load (lifting heavier, longer work days, more golf) and/or a relative overload due to an  increase in internal load (heightened stress, illness, hormonal influences). All of the factors mentioned above contribute to the capacity of the shoulder to handle load and the capacity can vary day to day with changing internal loads. For example high internal loads such as reduced sleep, increased work stress and getting the flu can lead to a decrease in capacity and as such may lead to relative overload and pain can develop from the complex interaction of these factors despite completing normal tasks or loads.

Management

Common to all presentations is the need to engage with the individual experiencing the symptoms, allowing the person to voice their needs, concerns and questions (2). In addition, patients should be given the opportunity to discuss their understanding of the cause of the symptoms, how quickly they expect to recover, the treatments they may consider to be effective, their goals and their thoughts on the treatment the clinician recommends. Clinicians should provide information and education relating to cause, prognosis and expected outcome and avoid ‘threatening’ language such as ‘acromion impinging and wearing away or tearing into the tendon’ (2). Hopefully this blog is a step in helping this education and understanding.

A structured exercise program is unequivocally the main intervention for RCRSP ( 26, 27, 28). There is a lack of consensus on dosage, frequency, method of delivery, acceptable pain tolerance, inter-exercise activity levels, and specific exercise inclusion has not been achieved. A study by Kuhn (2009) (30)  concluded that; exercise had statistically and clinically significant effects on pain reduction and improving function, but not on range of motion or strength, and manual therapy may augment the effects of exercise. A Hanratty study (29)  concluded that; strong evidence existed for exercise to decrease pain and improve function in the short-term, and moderate level evidence suggested that exercise resulted in short-term improvement in mental well-being and long-term improvement in function. Systematic reviews looking at exercise therapy show effectiveness for improving pain scores, active range of motion, and overall shoulder function at short-term (6–12 weeks) and long-term follow-ups (greater than 3 months) (38).

It can be useful to differentiate management of RCRSP according to irritability. Irritable cases of RCRSP  are commonly characterised by being easily aggravated and prolonged shoulder pain once provoked, together with night pain. As with all presentations load management (relative rest) is important and the aim is to identify a level of activity that reduces the amount of pain experienced. It is really important in these circumstances to consider the individual’s response to exercise and choose appropriate levels of loading. Exercise in the form of gentle loading, such as short lever exercises may be well tolerated when weight or movement selection is to the individual.  This and other examples of motor control exercises should not increase irritability and when appropriate should incorporate lower limb weight transfer (2). Fast or heavy loads can commonly be aggravating (2) and pharmacological intervention may be required to control symptoms. All medicine is associated with risk, including; adverse reactions, side effects and interactions, and the risks must be considered together with the intended benefits. Corticosteroids have been associated with deleterious effects on rotator cuff tendon tissue (31, 32). There is a worrying paucity of evidence to support injection therapy for the shoulder (2). Studies that have compared corticosteroid injection to placebo, anaesthesia or physiotherapy (exercise and manual therapy) tend to identify a small benefit in pain reduction in the short term but this benefit does not extend beyond 6-8 weeks (33, 34, 35).

Non-irritable RCRSP is characterised by mild to severe pain that increases with movement and no or minimal irritability. Pain and weakness is most commonly experienced in the direction of external rotation and elevation and any soreness with activity settles shortly after. Non-irritable RCRSP may benefit from a graduated shoulder strength program, initially without, then with, increasing weights and resistances. As pain decreases, range may be progressed as can the resistance. It is also beneficial to strengthen the opposite limb. Numerous exercise options are available and can strengthen shoulder muscles and the rotator cuff. A recent study has shown similar outcomes for high load versus low load strength work, meaning rehabilitation lifting very heavy weight may not be necessary for all (36). In both groups, significant within-group improvements were found in primary and secondary outcomes of pain with activity, pain at night, maximum pain, strength, and passive external ROM (36). The rotator cuff muscles have also been shown to have direction specific action; with anterior rotator cuff muscles (subscapularis) with higher recruitment in actions extending the arm, whilst posterior rotator cuff muscles (supraspinatus, infraspinatus) have increased activity into flexion (37). Practically this means training the rotator cuff can occur with flexion and extension exercises in addition or as an alternative to traditional rotation based exercises (37). Manual therapy can be used as an adjunct to assist in reduction in pain alongside exercise based management (38).

The large body of evidence suggests that rotator cuff related shoulder pain is common and responds well to gradual exercise based physiotherapy. Changes to the tendon (tear, tendinopathy and bursitis) are common features in those with and without pain. Whilst large full thickness strains are challenging individuals with RCRSP (bursitis, tendinopathy or small partial thickness tears) can have confidence of favourable recovery over 12 weeks.

Lewis Craig (APAM)

POGO Physiotherapist
Masters of Physiotherapy

Featured in the Top 50 Physical Therapy Blog

References

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